Vacuum cleaner motor assemblies and methods of operating same

ABSTRACT

A vacuum cleaner includes a housing, a debris chamber defined within the housing, a motor assembly connected to the housing and operable to generate airflow through the debris chamber, and a controller communicatively coupled to the motor assembly. The motor assembly includes a motor and an impeller. The controller includes a processor and a memory. The memory includes instructions that program the processor to operate the motor to cause the impeller to generate airflow through the debris chamber, detect an alert condition, and generate a human perceptible audible alert in response to the detected alert condition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/934,693 filed Nov. 13, 2019, entitled “VACUUM CLEANER MOTORASSEMBLIES AND METHODS OF OPERATING SAME,” which is incorporated hereinby reference in its entirety.

FIELD

The field of the disclosure relates generally to vacuum cleaners and,more particularly, to vacuum cleaner motor assemblies and methods ofoperating same.

BACKGROUND

Some known vacuum cleaners, and particularly the motor assemblies insuch vacuum cleaners produce electromagnetic interference at levels thatmay be unacceptable to some users or in some industries. Further, theelectromagnetic compatibility of such vacuum cleaners may be lower thandesired. Some vacuum cleaners are also not capable of meeting thetemperature, voltage, and current requirement of some users andindustries.

Moreover, vacuum cleaners typically do not communicate information tousers and may be frustrating to users. For example, some vacuum cleanerswill simply shut down when the motor overheats, leaving the user unableto continue vacuuming and not knowing why the vacuum stopped.

This background section is intended to introduce the reader to variousaspects of art that may be related to various aspects of the presentdisclosure, which are described and/or claimed below. This discussion isbelieved to be helpful in providing the reader with backgroundinformation to facilitate a better understanding of the various aspectsof the present disclosure. Accordingly, it should be understood thatthese statements are to be read in this light, and not as admissions ofprior art.

SUMMARY

According to one aspect, a vacuum cleaner includes a housing, a debrischamber defined within the housing, a motor assembly connected to thehousing and operable to generate airflow through the debris chamber, anda controller communicatively coupled to the motor assembly. The motorassembly includes a motor and an impeller. The controller includes aprocessor and a memory. The memory includes instructions that programthe processor to operate the motor to cause the impeller to generateairflow through the debris chamber, detect an alert condition, andgenerate a human perceptible audible alert in response to the detectedalert condition.

Another aspect is a controller for a vacuum cleaner including a motor,an impeller, and a debris chamber. The controller includes a processor,and a memory. The memory includes instructions that program theprocessor to operate the motor to cause the impeller to generate airflowthrough the debris chamber, detect an alert condition, and generate ahuman perceptible audible alert in response to the detected alertcondition.

Another aspect of this disclosure is a method of operating a vacuumcleaner including a motor, a battery, an impeller, and a debris chamber.The method includes operating the motor to cause the impeller togenerate airflow through the debris chamber, detecting an alertcondition of a plurality of alert conditions detectable by thecontroller, and generating a human perceptible audible alert in responseto the detected alert condition. The plurality of alert conditionsincludes a temperature of the motor equaling or exceeding a temperaturethreshold, a voltage of the battery being below a voltage threshold, amotor fault occurring, and a predetermined maintenance being due.

Various refinements exist of the features noted in relation to theabove-mentioned aspects. Further features may also be incorporated inthe above-mentioned aspects as well. These refinements and additionalfeatures may exist individually or in any combination. For instance,various features discussed below in relation to any of the illustratedembodiments may be incorporated into any of the above-described aspects,alone or in any combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example vacuum cleaner.

FIG. 2 is a side schematic view of the vacuum cleaner shown in FIG. 1.

FIG. 3 is a block diagram of the vacuum cleaner shown in FIG. 1.

FIG. 4 is a flow diagram of an example method of thermal protection andannunciation for the vacuum cleaner shown in FIG. 1.

FIG. 5 is a flow diagram of an example method of low voltageannunciation for the vacuum cleaner shown in FIG. 1.

FIG. 6 is a simplified diagram of the power source, the controller, andthe reverse polarity protection circuit of the vacuum cleaner shown inFIG. 1 with the correct polarity connection.

FIG. 7 is a simplified diagram of the power source, the controller, andthe reverse polarity protection circuit of the vacuum cleaner shown inFIG. 1 with the incorrect polarity connection.

FIG. 8 is a schematic sectional view of an example motor assemblysuitable for use in the vacuum cleaner shown in FIGS. 1-3.

FIG. 9 is a perspective view of the motor assembly shown in FIG. 8.

FIG. 10 is a top view of a circuit board assembly of the motor assemblyshown in FIGS. 8 and 9.

FIG. 11 is a bottom view of the circuit board assembly shown in FIG. 10.

FIG. 12 is an enlarged view of a portion of the circuit board assemblyshown in FIG. 10, illustrating conductive edge plating of the circuitboard assembly.

FIG. 13 is an enlarged view of a portion of the motor assembly shown inFIG. 9.

FIG. 14 is a perspective view of the motor assembly shown in FIG. 9 withan example electromagnetic shield connected thereto.

FIG. 15 is a perspective view of the motor assembly shown in FIG. 9 withanother example electromagnetic shield connected thereto.

FIG. 16 is a perspective view of the motor assembly shown in FIG. 9,illustrated in a disassembled state.

FIG. 17 is a bottom perspective view of the motor housing of the motorassembly shown in FIG. 9.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an example vacuum cleaner 100, shown inthe form of a backpack vacuum cleaner. Although the vacuum cleaner 100is shown and described herein with reference to a backpack mountedvacuum cleaner, vacuum cleaners consistent with this disclosure may beembodied in other types and in other combinations including, for exampleand without limitation, vehicular or automotive vacuum cleaners, wet/dryvacuum cleaners, canister vacuum cleaners, and upright vacuum cleaners.By way of example, aspects of the vacuum cleaners, such as the motorassemblies and control methods disclosed herein, may be implemented inautomotive or transportation vacuum cleaners, such as those disclosed inU.S. Pat. Nos. 9,751,504; 10,328,907; and 10,099,659, the disclosures ofwhich are hereby incorporated by reference in their entirety.

In the example embodiment, vacuum cleaner 100 includes a vacuum cleanerassembly 102 that is carried on a user's back via a harness or backpackassembly 104, and a vacuum conduit 106 connected to the vacuum cleanerassembly 102. The vacuum conduit 106 may generally include any suitableconduit for directing suction and/or forced air generated by the vacuumcleaner 100, including, for example and without limitation, vacuumhoses, vacuum wands or tubes, surface cleaning tools, and combinationsthereof. In the illustrated embodiment, the vacuum conduit 106 includesa hose 108 extending from a top of the vacuum cleaner assembly 102, avacuum cleaner wand 110 connected to the hose 108, and a vacuum cleanerfloor tool 112 connected to a distal end of the wand 110.

The backpack assembly 104 is sized and shaped to be worn by a user ofthe vacuum cleaner 100 (e.g., on the user's back or shoulders) tofacilitate carrying the vacuum cleaner 100 during use. In theillustrated embodiment, the backpack assembly 104 includes two shoulderstraps 114 and a waist belt 116 for securing the backpack assembly 104and vacuum cleaner 100 to the torso of a user. In other embodiments, thebackpack assembly 104 may have any suitable configuration that enablesthe vacuum cleaner 100 to function as described herein.

With additional reference to FIGS. 2 and 3, the vacuum cleaner assembly102 includes a housing 202, a suction unit 204 enclosed within thehousing 202, a controller 206, and a power source 208. The componentsand connections shown in FIG. 3 are a functional example only. Otherembodiments may include different components, more or fewer components,components connected to different components, and/or different polarityconnections.

The housing 202 defines an inlet 210, at least one exhaust or outlet212, and a debris chamber 214 connected in fluid communication betweenthe inlet 210 and the outlet 212. In the example embodiment, the inlet210 is defined at a top of the housing 202, and the housing 202 includestwo outlets 212 defined adjacent a bottom of the housing 202. In otherembodiments, the inlet 210 and the outlet(s) 212 may be defined at anysuitable portion of the vacuum cleaner 100 that enables the vacuumcleaner 100 to function as described herein. Further, the vacuum cleaner100 may include more than or fewer than two outlets 212.

In the illustrated embodiment, the housing 202 includes an access dooror lid 218 that provides access to the debris chamber 214, for example,to empty debris collected within the debris chamber 214. The inlet 210is defined in the lid 218 in the example embodiment. Further, theexample housing 202 is adapted to receive a filter 220 within the debrischamber 214 to filter out fine debris and small particles from the airflow through the housing 202. In the illustrated embodiment, the filter220 is a bag filter, although the vacuum cleaner 100 may be operablewith other types of filters, including, for example and withoutlimitation, cartridge filters.

The suction unit 204 is operable to generate airflow (indicated byarrows in FIG. 2) through the housing 202 from the inlet 210 to theoutlet 212 so as to draw debris into the debris chamber 214 through theinlet 210 by way of the vacuum conduit 106 (shown in FIG. 1). Thesuction unit 204 includes a fan or impeller 222 and a motor 224operatively connected to the impeller 222 (collectively referred toherein as a “motor assembly”) to drive the impeller 222 and generateairflow through the housing 202. The motor assembly is connected to thehousing 202 and positioned adjacent the debris chamber 214 such that theimpeller 222 receives airflow through an impeller inlet 226 defined bythe housing 202. In certain embodiments, the motor assembly may also beadapted to operate in a “reverse” mode in which the motor assemblygenerates airflow from the outlet 212 to the inlet 210, so as to enablethe vacuum cleaner 100 to operate as a blower.

The controller 206 is generally configured to control one or moreoperations or processes of the vacuum cleaner 100, as described furtherherein. In some embodiments, for example, the controller 206 receivesuser input from a user interface 302 of vacuum cleaner 100, and controlsone or more components of vacuum cleaner 100 in response to such userinputs. The user interface 302 includes a power switch 314, a speedselection switch 316, and a display 318. The power switch 314 is asingle pole single throw (SPST) momentary switch operated by the user toturn the vacuum cleaner 100 on and off. Alternatively, the power switch314 may be a maintained switch rather than a momentary switch. The speedselection switch 316 is a dual pole dual throw (DPDT) switch operable bythe user to select an operation speed of the motor 224 of the vacuumcleaner 100. The display 318 is a visual display for displayinginformation about the vacuum cleaner 100 to the user. In the exampleembodiment, the display 318 is a light emitting diode (LED).Alternatively, the display 318 may be a plurality of LEDs, a displayscreen (such as an LED panel, a liquid crystal display (LCD) panel, orthe like), or any other display suitable for visually displayinginformation to the user of the vacuum cleaner 100.

In some embodiments, the controller 206 controls the supply of powerfrom power source 208 to vacuum suction unit 204 based on user inputreceived from the user interface 302. For example, the controller 206operates the motor 224 in response to user input received from the powerswitch 314 and the speed selection switch 316. The controller 206 mayregulate or control electrical power supplied to vacuum cleaner 100,such as from power source 208. For example, the controller 206 of thevacuum cleaner 100 may include one or more power converters orregulators configured to control or regulate the electrical powersupplied to components of the vacuum cleaner 100, such as the motor 224of vacuum suction unit 204. In some embodiments, for example, thecontroller 206 may include one or more DC power converters or regulatorsconfigured to control or regulate DC power supplied by the power source.Such power converters and regulators may be incorporated or integratedwithin components of the vacuum cleaner 100, such as the vacuum suctionunit 204 and/or within the motor 224.

The controller 206 may generally include any suitable computer and/orother processing unit, including any suitable combination of computers,processing units and/or the like that may be operated independently orin connection within one another. The controller 206 may include one ormore processor(s) 304 and associated memory device(s) 306 containinginstructions that cause the processor 304 (i.e., “configure theprocessor” or “program the processor”) to perform a variety ofcomputer-implemented functions (e.g., performing the calculations,determinations, and functions disclosed herein). As used herein, theterm “processor” refers not only to integrated circuits, but also refersto a controller, a microcontroller, a microcomputer, a programmablelogic controller (PLC), an application specific integrated circuit, andother programmable circuits. Additionally, the memory device(s) 306 ofcontroller 206 may generally be or include memory element(s) including,but not limited to, computer readable medium (e.g., random access memory(RAM)), computer readable non-volatile medium (e.g., a flash memory), afloppy disk, a compact disc-read only memory (CD-ROM), a magneto-opticaldisk (MOD), a digital versatile disc (DVD) and/or other suitable memoryelements. Such memory device(s) 306 may generally be configured to storesuitable computer-readable instructions that, when implemented by theprocessor(s), configure or cause the controller 206 to perform variousfunctions described herein including, but not limited to, controllingvacuum cleaner 100, controlling operation of vacuum suction unit 204,receiving inputs from user interface 302, providing output to anoperator via user interface 302, and/or various other suitablecomputer-implemented functions.

The controller 206 includes a communications interface 308.Communications interface 308 allows the vacuum cleaner 100 (and moreparticularly, the controller 206) to communicate with remote devices andsystems as part of a wired or wireless communication network. Wirelessnetwork interfaces may include a radio frequency (RF) transceiver, aBluetooth® adapter, a Wi-Fi transceiver, a ZigBee® transceiver, a nearfield communication (NFC) transceiver, an infrared (IR) transceiver,and/or any other device and communication protocol for wirelesscommunication. (Bluetooth is a registered trademark of Bluetooth SpecialInterest Group of Kirkland, Washington; ZigBee is a registered trademarkof the ZigBee Alliance of San Ramon, California.) Wired networkinterfaces may use any suitable wired communication protocol for directcommunication including, without limitation, USB, RS232, I2C, SPI,analog, and proprietary I/O protocols. Moreover, in some embodiments,the wired network interfaces include a wired network adapter allowingthe computing device to be coupled to a network, such as the Internet, alocal area network (LAN), a wide area network (WAN), a mesh network,and/or any other network to communicate with remote devices and systemsvia the network. Controller 206 transmits and receives communicationsover the communication network using messages formatted according to anappropriate network communication protocol. In some embodiments, thenetwork communication protocol is an Ethernet communication protocol oran Institute of Electrical and Electronics Engineers (IEEE) 802.11 basedcommunication protocol. In some embodiments, the communicationsinterface 308 includes wired and wireless communications interfaces. Insome embodiments, the communications interface 308 includes a wiredcommunication interface for communicative connection to a communicationinterface in an automobile.

The communications interface 308 may be used, for example, forcommunicating diagnostics information, providing the serial number ofthe vacuum cleaner 100, providing maintenance performed information,providing firmware version information, receiving firmware updates andreprogramming, and providing motor 224 operation/fault statusinformation to a diagnostic/monitoring device, or the like.

The controller 206 and/or components of controller 206 may be integratedor incorporated within other components of the vacuum cleaner 100. Insome embodiments, for example, controller 206 may be incorporated withinthe vacuum suction unit 204 or the motor assembly.

The power source 208 is configured to supply electrical power tocomponents of the vacuum cleaner 100, such as the motor 224 and thecontroller 206, and may generally include any suitable power source thatenables the vacuum cleaner 100 to operate as described herein. Suitabletypes of power sources include, for example and without limitation, DCpower sources, such as battery packs, and AC power sources, such asmains AC electricity from a household or commercial wall outlet. Areverse polarity protection circuit 326 protects the controller 206 andother components of the vacuum cleaner from damage caused by the powersource 208 being incorrectly connected to the controller 206 with theincorrect polarity. The reverse polarity protection circuit 326 will befurther described with respect to FIG. 6.

The illustrated vacuum cleaner 100 is a “cordless” vacuum cleaner thatincludes a portable power source, shown in the form of a battery 118removably connected to a battery receptacle 120 defined by the housing202. The battery 118 of the example embodiment is a direct current (DC)source battery configured to supply direct current to the vacuum cleaner100. The battery 118 may have any suitable DC battery construction thatenables the vacuum cleaner 100 to function as described herein. Forexample, the battery may include, without limitation, one or morelithium-ion batteries, nickel-metal hydride batteries, lead-acidbatteries, lithium-metal batteries, supercapacitors or othercapacitor-based voltage sources, lithium nickel manganese cobalt oxidebatteries, lithium nickel cobalt aluminum oxide batteries, and any othersuitable DC battery construction that enables the vacuum cleaner 100 tofunction as described herein. In this embodiment, the battery 118 is arechargeable lithium-ion battery that includes a plurality oflithium-ion cells.

The vacuum cleaner 100 includes a power cord for supplying AC power,converted to DC, to charge the battery, to supply power to operate themotor 224, and/or to power other operational components of the vacuumcleaner. Thus, the vacuum cleaner 100 may be selectively operated in acordless mode, in which the battery 118 is electrically connected to thevacuum cleaner 100, and a corded mode, in which a power cord iselectrically connected to the vacuum cleaner 100 and supplies AC powerto the vacuum cleaner 100 (e.g., from a wall outlet). Other embodimentsmay be operated only from a battery or only from AC power.

The illustrated vacuum cleaner 100 also includes a plurality of sensors228, 230, 232 connected to the controller 206. The sensors 228, 230, 232may provide feedback to the controller 206 regarding operation of thevacuum cleaner 100, and the controller 206 may control the vacuumcleaner 100 based on feedback received from the sensors 228, 230, 232.Sensors 228, 230, and 232 may include, for example and withoutlimitation, proximity sensors, pressure sensors, temperature sensors,voltage sensors, and active or passive current sensors.

The vacuum cleaner 100 includes a drive circuit 320 for powering themotor 224 of the suction unit 204. The drive circuit includes aplurality of switches 322 for selectively energizing coils (not shown)of the motor 224 to drive the motor 224. In the example embodiment, theswitches 322 are metal oxide semiconductor field effect transistors(MOSFETs). Alternatively, any other switch suitable for driving themotor 224 may be used. For clarity of illustration, only two switches322 are shown in FIG. 3, but the drive circuit 320 will typicallyinclude more than two switches 322 (e.g., six switches 322 for a threephase brushless DC motor), and the drive circuit 320 may include anynumber of switches useful to drive the motor 224. A temperature sensor324 detects the temperature of one or more drive component associatedwith the motor. Specifically, temperature sensor 324 is positioned nearthe switches 322 to detect the temperature of the switches 322 andprovide the detected temperature to the controller 206. In someembodiments, the temperature sensor 324 includes more than onetemperature sensor 324, each of which is positioned near one or moredifferent switches 322. For example, the drive circuit 320 may includeone temperature sensor 324 for each switch 322, one temperature sensor324 for each pair of switches 322, etc. In the example embodiment, thetemperature sensor 324 is a thermistor thermally coupled to the switches322 by a thermally conductive room-temperature-vulcanized (RTV)component or a thermally conductive adhesive. Alternatively, thetemperature sensor 324 may be a resistance temperature detector (RTD), athermocouple, or any other sensor suitable for measuring temperature.Although illustrated as a separate component, the drive circuit 320 maybe incorporated into the controller 206, the suction unit 204, or themotor 224.

To operate the vacuum cleaner 100, the user depresses the power switch314. In the example embodiment, the power switch 314 is a momentaryswitch, which sends a signal to the controller 206 only when the userdepresses the power switch 314. Generally, upon receiving the signalfrom the power switch 314, the controller toggles the on/off state ofthe vacuum cleaner 100. That is, if the vacuum cleaner 100 is off,depressing the power switch 314 provides a signal that the controller206 interprets as a request to turn on the vacuum cleaner 100. When thevacuum cleaner 100 is on, depressing the power switch 314 provides asignal that the controller 206 interprets as a request to turn off thevacuum cleaner 100.

To avoid changing the state of the vacuum cleaner 100 due tounintentional depression of the power switch 314, the controller 206times how long the power switch 314 is depressed (referred to as the“depression time”) and compares the depression time to a threshold time.If the depression time equals or exceeds the threshold time, thecontroller 206 interprets the depression as a request to toggle theon/off state of the vacuum cleaner 100, and the controller 206 togglesthe on/off state of the vacuum cleaner 100. If the depression time isless than the threshold time, the controller 206 interprets thedepression of the power switch 314 as an unintentional depression, andthe controller 206 does not toggle the on/off state of the vacuumcleaner 100. In the example embodiment, the threshold is a predeterminedthreshold that is the same for turning the vacuum cleaner 100 on andoff. In some embodiments, the predetermined threshold is two seconds.Other embodiments include a predetermined threshold that is shorter orlonger than two seconds. Alternatively, the threshold time for turningthe vacuum cleaner 100 on may be different than the threshold forturning the vacuum cleaner 100 off. Moreover, in some embodiments, thethreshold time is not predetermined and may be varied based, forexample, how long the user depressed the power switch 314 in previousinstances, the condition of the vacuum cleaner (e.g., whether it ismoving, its orientation relative to the ground, or other conditionssuggestive of whether or not the user intends to continue or ceasevacuuming, or the like), or based on any other suitable variable fordistinguishing between intentional and unintentional presses of thepower switch 314.

The speed at which the motor 224 operates is selectable by the userusing the speed selection switch 316. The speed selection switch 316 inthe example embodiment is a DPDT switch that connects and disconnects aspeed select pin of the controller 206 to ground. The controller 206detects whether or not the speed select pin is connected to ground. Thatis, a first pole of the speed selection switch 316 has one terminalconnected to ground and the speed select pin, while the other terminalis only connected to the speed select pin of the controller 206 (i.e.,the speed select pin is floating). Power is provided to the controller206 through the first pole (the ground/return line is continuouslyconnected to the controller 206). On the second pole, both terminals areconnected to the power input of the controller 206. The grounded and notgrounded (i.e., floating) states of the speed select pin from the firstpole represent high and low (or low and high) speed selections. The DPDTswitch is an on-off-on type DPDT switch, and the middle/off positionfunctions as a power disconnect position that opens the power circuit byleaving the power input and the speed select pin of the controller 206open (i.e., floating) to prevent a battery of the power source 208 (inbattery powered embodiments) from being drained when the vacuum cleaner100 is not being operated.

Other embodiments do not include the speed selection switch 316. Rather,the speed is selected by particular timed depressions of the powerswitch 314 or using a potentiometer and an analog to digital converter(ADC).

In embodiments using the timed depression of the power switch 314, forexample, when the vacuum cleaner 100 is on (i.e. the motor 224 isrunning), a depression of the power switch 314 longer than a settingthreshold, but shorter than the threshold to turn off the vacuum cleaner100 is treated by the controller 206 as a request to cycle to a nextspeed setting of the motor 224. The cycling may be by increment (e.g.,low to medium) or by decrement (e.g., medium to low). For example, ifthe threshold for turning the vacuum cleaner 100 is two seconds, thesetting threshold may be one-half of a second. With the vacuum cleaner100 on, depressing the power switch 314 for at least half a second (butless than two seconds) changes the speed of the motor to a next levelabove or below (depending on the particular embodiment).

In embodiments using a potentiometer and an ADC, the potentiometerprovides a continuously variable (by the user adjusting the resistanceof the potentiometer) analog signal to the ADC. This signal is convertedby the ADC to a digital signal corresponding to the magnitude of theanalog signal, and the digital signal is provided to the controller 206.The controller 206 then sets the speed of the motor 224 based on thevalue of the digital signal (and correspondingly based on the magnitudeof the analog signal).

In some embodiments, the power switch 314 is also used to instruct thecontroller 206 to perform diagnostics on the vacuum cleaner 100. Forexample, when the vacuum cleaner 100 is off, depressing the power switch314 for a length of time longer than a diagnostic threshold isunderstood by the controller 206 as a command to perform diagnostics andreport results and/or recommended maintenance (such as via the display318). Alternatively, the diagnostic results and recommendations may bestored in memory 306 for retrieval by the user or a service technician.The diagnostic threshold is greater than the threshold for turning onthe vacuum cleaner 100. In such embodiments, the diagnostic thresholdalso functions as a maximum threshold for turning on the vacuum cleaner100. That is, to turn on the vacuum cleaner, the power switch 314 mustbe depressed for longer than the threshold, but less than diagnosticthreshold. In an example, the threshold is two seconds and thediagnostic threshold is ten seconds. Alternatively, any other suitablethresholds may be used.

The controller 206 is also configured to prevent operation of the vacuumcleaner 100 when the filter 220 is not installed in the vacuum cleaner100. A sensor (e.g., sensor 228) is positioned to detect when the filter220 is installed and to provide a signal to the controller 206 when thefilter 220 is not installed. Alternatively, the sensor may provide asignal when the filter 220 is installed and not provide a signal whenthe filter is absent. In an example embodiment, the sensor is a switchconnected in series to a sensing pin of the controller 206. When thefilter 220 is installed, the filter 220 depresses the switch, closingthe circuit connection to the sensing pin, and thereby provides a signalto the controller that the filter 220 is installed. When the filter 220is absent (or improperly installed), the switch is not depressed, thecircuit is open, and no signal is provided to the sensing pin of thecontroller 206. Alternatively, the switch may be positioned to detectwhether a cover (or door) of debris chamber 214 (in which the filter 220is located) is open or closed. The controller 206 is configured toprevent operation of the motor 22 when the cover is open and allowoperation when the cover is closed. By preventing operation of thevacuum cleaner 100 when the filter 220 is not installed or the cover isopen, debris may be prevented from contaminating the motor and/orstriking the impeller 222 or other elements of the suction unit 204.

The controller 206 provides thermal protection for the motor 224 anddrive circuit 320, and communicates thermal protection relatedinformation to the user of the vacuum cleaner 100. The controller 206monitors the temperature of the switches 322 of the drive circuit 320using the temperature sensor 324. Generally, when the detectedtemperature exceeds a first temperature threshold, the controller 206reduces the power output of the motor 224 and warns the user of anexcess temperature condition. If the temperature does not drop below thefirst temperature threshold in a threshold time, or if the temperatureexceeds a second temperature threshold, the controller stops the motor224 to avoid damage to the motor due to the excessive temperature.

FIG. 4 is a flow diagram of an example method 400 of thermal protectionfor use with the vacuum cleaner 100. The method 400 may be used withother vacuum cleaners, and the vacuum cleaner may use other methods forproviding thermal protection and communication. At 402, the controller206 is operating the motor 224 under normal operation, during which acounter is set at zero. At 404, the controller checks the motor 224temperature using the temperature sensor 324. At 406, the controller 206compares the detected temperature to a first temperature threshold T1.The temperature T1 is a predetermined threshold greater than expectedduring normal operation, but lower than a temperature at which the motor224 should be shut down immediately (second temperature threshold T2).In the example embodiment, the first temperature threshold T1 is 85° C.and the second temperature threshold T2 is 100° C. In other embodiments,T1 and T2 may be any other temperatures suitable for protecting themotor 224 and the drive circuit 320 from thermal damage, and may beselected based on the power ratings and temperature ratings of thecomponents of the drive circuit 320 and the motor 224. If thetemperature is less than T1, the counter is cleared and the controller206 continues normal operation at 402. Other embodiments may includemore than two temperature thresholds or temperature thresholds havingdifferent temperature values. Some embodiments may include differentwarnings (e.g., different sounds, different lights, and the like) forthe different temperature ranges represented by the more than twotemperature thresholds.

If the temperature is greater than or equal to T1, a temperatureprotection and annunciation begins. The controller 206 compares thetemperature to the second temperature threshold T2 at 410. If thetemperature is greater than or equal to T2, the controller 206 shutsdown the motor 224 at 412. If the temperature is less than T2, at 414,the controller 206 determines if the counter is less than 10. If thecounter equals or exceeds 10, the controller 206 shuts down the motor224 at 412.

If the counter is less than 10, the controller 206 reduces the poweroutput for the motor 224 at 416. In the example embodiment, the power isreduced by 75% (i.e., it is operated at 25% of full power). In otherembodiments, the power output may be reduced by a larger or smallerpercentage. At 418, the controller 206 waits for a period of time whilethe motor 224 is operated at the reduced power. The period of time is apredetermined, fixed period of time in the example embodiment and is 1.5seconds. In other embodiments, the period of time may be a shorter orlonger fixed, predetermined period of time. In still other embodiments,the period of time may be a variable period of time, such as a period oftime that increases as the amount by which the detected temperatureexceeds the first temperature threshold T1 increases. At 420, afterwaiting for the period of time, the controller 206 resumes full poweroperation of the motor 224. Alternatively, the controller 206 mayincrease the motor 224 power above the reduced power, but below fullpower. At 422, the counter is incremented by one and the method returnsto 404 to check the temperature and again compare the temperature to thefirst temperature threshold T1. Although only one counter loop is shownand described, more than one counter loop (e.g., sub-routine loops) maybe included.

Steps 416, 418, and 420 both facilitate reducing the temperature of themotor 224 and announce to the user that motor 224 temperature is highand temperature protection is engaged. By running the motor 224 at areduced power level for the waiting period of step 418, less power isdissipated and the temperature may decrease. During this time period,the motor is derated to run at a power level lower than its normal ratedpower level. Reducing the power at 416, waiting at 418, and thenreturning to full power at 420 produces a tactile and audible alert tothe user. That is, the vibration of the vacuum cleaner 100 and the pitchof the running motor 224 will change in a pulse pattern from thevibration and sound during normal operation at 402. Thus, the user isalerted to the condition and may take action (such as turning off thevacuum cleaner 100, clearing an airway obstruction, cleaning orreplacing the filter, or the like. Moreover, the pulsing of the motor224 will also pulse the vacuum suction strength, which may help clearsoft obstructions that are restricting airflow and contributing to theincreased temperature of the motor. The pulsing of the suction strengthcan create a hammering force on soft obstructions to overcome staticforce and push the obstructions past airflow restriction points.

Other embodiments may include more than one temperature threshold eachassociated with a different power reduction or a different wait time. Insuch embodiments, as the threshold increases, the power reduction and/orthe wait time increases. Moreover, in some embodiments, a separatetemperature threshold (a “reset threshold”) lower than the firsttemperature threshold T1 is used at 406 when the counter is equal to orgreater than one. Thus, such embodiments include hysteresis such thatonce the temperature exceeds T1, the temperature must drop to a resettemperature below T1 before the thermal protection and annunciation loopcan be exited. This will avoid the vacuum cleaner pulsing (416-420) oneor a few times to drop the temperature below T1 and then operating for abrief time before the temperature again rises above T1. For example, inan embodiment where T1 is 85° C., the reset threshold may be 75° C.

In some embodiments, warnings to the user about an overtemperature eventmay additionally or alternatively be provided to the user through theuser interface 302 of the vacuum cleaner 100. For example, anovertemperature warning may be presented to the user via the userinterface 302 when the controller 206 detects the temperature exceeds T1at 406. The warning may be presented using the display 318. When thedisplay 318 is an LED or an array of LEDs, the warning may be present bya particular pattern of blinking, lighting a particular LED associatedwith a temperature warning, lighting a particular color LED, or lightinga particular pattern of LEDs. If the display 318 is an LCD panel, an LEDpanel, or other similar display panel, the warning may be displayed as atext warning readable by the user. In other embodiments, the userinterface 302 includes an audio output device (not shown), such as apiezoelectric device, to produce human audible sounds to conveyinformation about an alert condition (e.g., a high temperature, a lowbattery voltage, a motor fault, an upcoming maintenance requirement, orthe like) to the user. In such embodiments, the audio output device mayoutput a unique pattern of sound or a unique tone to indicate thatthermal protection has been started (e.g., when the temperature exceedsor equals T1). Alternatively, the audio output device may output aspoken warning to the user (using a recorded announcement or atext-to-speech announcement). Additionally, or alternatively, the userinterface 302 may include a vibration motor (not shown) to provideinformation to a user. Similar to the audio output of the audio outputdevice, the vibration motor may output a unique pattern of vibration toindicate that thermal protection has been started (e.g., when thetemperature exceeds or equals T1).

The controller 206 provides low battery voltage information to the userof the vacuum cleaner 100. Generally, the controller 206 monitors thevoltage of the battery 118 and warns the user when the battery voltageis lower than a predefined, fixed threshold voltage to warn the userthat the battery is almost discharged. Thus, the user is warned of theimpending stoppage of the vacuum cleaner 100 operation and has time toreplace the battery with a charged battery, plug in the vacuum cleanerto operate off AC power (in embodiments with AC power operation) andcharge the battery, or attempt to finish vacuuming before the battery isexhausted.

FIG. 5 is a flow diagram of an example method 500 of informing the userof a low battery voltage. The method 500 may be used with other vacuumcleaners, and the vacuum cleaner 100 may use other methods forcommunicating a low battery voltage to the user.

At 502, the controller 206 is operating the motor 224 under normaloperation, during which a counter is set at zero. At 504, the controllerchecks the voltage of the battery 118. At 506, the controller 206compares the detected voltage to a low voltage threshold V1. The lowvoltage threshold V1 is selected to provide the low voltage warningapproximately five minutes before the battery will be discharged to thepoint that the vacuum cleaner 100 can no longer operate. Thus, the valueof the low voltage threshold V1 depends on the particular battery 118used in the vacuum cleaner 100. For a 36 volt, 6 amp hour (Ah) battery,V1 is approximately 32.15 volts, while V1 is approximately 30.73 voltsfor a 36 volt 12aH battery. The low voltage threshold V1 may also differdepending on the speed setting at which the vacuum cleaner is beingoperated. In other embodiments, V1 may be selected to correspond to adifferent amount (more or less than five minutes) of remainingoperational time before the battery 118 is discharged. In still otherembodiments, the low voltage threshold V1 is selected to correspond to aremaining capacity or voltage of the battery 118 relative to its initialcapacity or voltage, such as ten percent of initial capacity,twenty-five percent of initial capacity, eighty-five percent of initialvoltage, ninety percent of initial voltage, etc..

In other embodiments, the user may select the low voltage threshold V1to adjust the length of time between a warning and a depleted battery118, or may disable the low voltage warning completely. Thus, the step506 may include selecting the low voltage threshold V1 corresponding tothe particular battery 118 installed in the vacuum cleaner 100 and thecurrent speed setting of the vacuum cleaner 100. In other embodiments,the low voltage threshold V1 is not predetermined. Rather, thecontroller 206 monitors the battery voltage decay rate during operationand calculates low voltage threshold V1 to provide a warning a certainlength of time (e.g., five minutes) before the battery is drained basedon the monitored decay rate.

If the detected voltage is greater than the low voltage threshold V1,the method returns to 502 and the controller 206 continues normaloperation of the motor 224. If the detected voltage is less than orequal to V1, the controller 206 sets a counter equal to zero at 507. At508, the controller 206 reduces the power output for the motor 224. Inthe example embodiment, the power is reduced by 75% (i.e., it isoperated at 25% of full power). In other embodiments, the power outputmay be reduced by a larger or smaller percentage. At 510, the controller206 waits for a first period of time (TIME1) while the motor 224 isoperated at the reduced power. The first period of time is apredetermined, fixed period of time in the example embodiment and is 1.5seconds. In other embodiments, the first period of time may be a shorteror longer fixed, predetermined period of time. In still otherembodiments, the first period of time may be a variable period of time,such as a period of time that increases as the amount by which thedetected voltage is below V1 increases. At 512, after waiting for thefirst period of time, the controller 206 resumes full power operation ofthe motor 224. Alternatively, the controller 206 may increase the motor224 power above the reduced power, but below full power. As explainedabove with respect to FIG. 4, this reduction of power followed by areturn to full power produces a tactile and audible warning perceptibleby the user as a vibrational and audible pulsing.

At 514, the counter is incremented by one. The controller 206 determinesat 516 if the counter is greater than three. If the counter is notgreater than three, the controller 206 returns to 508. Thus, thecontroller will perform the reduction of power and resumption of fullpower four times before step 516 will return a yes answer. When thecounter is greater than three, the controller waits for a second periodof time (TIME2) at 518 before returning to 507 and resetting the counterto 0. The second period of time is longer than the first period of time.In the example, the second period of time is sixty seconds. In otherembodiments, the second period of time may be longer or shorter, so longas it is noticeably (by the user) longer than the first period of time.The second period of time introduces a break in the pulsing caused bysteps 508-512. As a result, the pulsing pattern in the method 500 willdiffer from the continuous pulsing in the method of 400. Thus, the usermay distinguish a warning about a low battery voltage from a warningabout an overtemperature condition. Although only one counter loop isshown and described, more than one counter loop (e.g., sub-routineloops) may be included. Other embodiments may include more than two timeperiods.

Warnings to the user about a low battery voltage may additionally oralternatively be provided to the user through the user interface 302 ofthe vacuum cleaner 100. For example, a low battery voltage may bepresented to the user via the user interface 302 when the controller 206detects the voltage is less than or equal to V1 at 506. The warning maybe presented using the display 318. When the display 318 is an LED or anarray of LEDs, the warning may be present by a particular pattern ofblinking, lighting a particular LED associated with a low batteryvoltage, lighting a particular color LED, or lighting a particularpattern of LEDs. If the display 318 is an LCD panel, an LED panel, orother similar display panel, the warning may be displayed as a textwarning readable by the user. In other embodiments, the user interface302 includes an audio output device (not shown), such as a piezoelectricdevice, to produce human audible sounds to convey information to theuser. In such embodiments, the audio output device may output a uniquepattern of sound or a unique tone to indicate that a low battery voltagehas been detected (e.g., when the voltage is less than or equal to V1).Alternatively, the audio output device may output a spoken warning tothe user (using a recorded announcement or a text-to-speechannouncement). Additionally, or alternatively, the user interface 302may include a vibration motor (not shown) to provide information to auser. Similar to the audio output of the audio output device, thevibration motor may output a unique pattern of vibration to indicatethat a low battery voltage has been detected (e.g., when the voltage isless than or equal to V1).

The user interface 302 may also be used by the controller 206 to provideother information to the user of the vacuum cleaner 100. For example,when the user depresses the power switch 314, there will typically be adelay before the motor 224 begins rotation sufficient to be felt orheard by the user. Thus, in some embodiments, the display 318 displaysan operating notification indicating that the vacuum cleaner 100 isoperating (and more specifically, that the motor 224 is on). Forexample, if the display 318 is an LED, the LED may blink with aparticular pattern. Alternatively, the operating notification mayinclude lighting a particular LED associated with a low battery voltage,lighting a particular color LED, or lighting a particular pattern ofLEDs. If the display 318 is an LCD panel, an LED panel, or other similardisplay panel, the operating notification may be displayed as a textwarning readable by the user. In embodiments in which the user interface302 includes an audio output device, such as a piezoelectric device, theaudio output device may be used to output a unique pattern of sound or aunique tone as the operating notification. Alternatively, the audiooutput device may output a spoken operating notification to the user(using a recorded announcement or a text-to-speech announcement). Inembodiments including a vibration motor, the vibration motor may outputa unique pattern of vibration as the operating notification. Similartechniques may be used with whichever display, audio, vibrational orother elements are included in the user interface to inform the user ofa motor fault (such as a locked rotor), of an upcoming maintenancerequirement, of a status of the filter 220, of a cumulative number ofhours that the vacuum cleaner has been operated, of a clogged filter orhose (e.g., as measured by a pressure differential filter), or of anyother suitable information related to the vacuum cleaner 100 and itsoperation.

As discussed above with respect to FIG. 3, the reverse polarityprotection circuit 326 protects the controller 206 and other componentsof the vacuum cleaner from damage caused by the power source 208 beingincorrectly connected to the controller 206 with the incorrect polarity.The reverse polarity protection circuit 326 will be discussed withreference to FIG. 6, which is a simplified diagram of the reversepolarity protection circuit 326, the power source 208, and thecontroller 206.

The power source 208 includes a positive terminal 600 and a negativeterminal 602. The controller 206 includes a positive terminal 604 and anegative terminal 606 (also referred to as a “return terminal”). Thereverse polarity protection circuit 326 is connected between the powersource 208 and the controller 206 to protect against the controller'spositive terminal 604 being connected to the power source's negativeterminal 602 and the controller's negative terminal 606 being connectedto the power source's positive terminal 600. The reverse polarityprotection circuit 326 includes an N-type MOSFET 608 connected in thereturn path of the controller 206. Specifically, source (S) of theMOSFET 608 is connected to the negative terminal 606 of the controller206, the gate (G) of the MOSFET 608 is connected to the expectedpositive terminal (e.g., the trace, wire, or connector that is intendedto connect to the positive terminal 600) of the power source 208, andthe drain (D) of the MOSFET 608 is connected to the expected negativeterminal (e.g., the trace, wire, or connector that is intended toconnect to the negative terminal 602) of the power source 208. Althoughnot shown for clarity of illustration, the gate G is connected to theexpected positive terminal through a clamped and protected connection,and is referenced to the source S through a resistive connection. Theclamped and protected connection can be provided using any suitableelectrical components, including, for example and without limitation,Zener diodes, rectifier diodes, switching diodes, TVS diodes, transorbs,varistors, and voltage dividers (varistors, resistors) configured incombinations of series/parallel arrangements, and unipolar or bipolarcomponents.

When the controller 206 is connected to the power source 208 with thecorrect polarity (as illustrated in FIG. 6), the MOSFET 608 is placedinto saturation mode, which electrically acts as a short circuit. Thus,under correct polarity, the MOSFET 608 connects the negative terminal606 of the controller 206 to the negative terminal 602 of the powersource 208 by a low resistance (e.g., a few milliohms) path through theMOSFET's intrinsic junction. This short-circuit (very low resistance)path allows normal current flow and hence normal circuitry operation.

When the controller 206 is connected to the power source 208 with theincorrect polarity, the gate G is connected to the negative terminal 602and the drain D is connected to the positive terminal 600, as shown inFIG. 7. With this incorrect connection, the MOSFET 608 is placed intocutoff mode, which electrically acts as an open circuit. Thus, theMOSFET 608 connects the negative terminal 606 of the controller 206 tothe positive terminal 600 of the power source 208 by a very highresistance (e.g., mega-ohms) path through the MOSFET's intrinsicjunction. This open-circuit (very high resistance) prevents damagingreverse polarity current from flowing and prevents the controller 206from operating.

An example motor assembly 800 suitable for use in the vacuum cleaner ofFIGS. 1-3 is illustrated in FIGS. 8 and 9. The motor assembly 800includes a motor casing or housing 802, a motor 804 (e.g., motor 224,shown in FIGS. 2 and 3) coupled to and at least partially enclosedwithin the motor housing 802, a fan or impeller 806 (e.g., impeller 222,shown in FIGS. 2 and 3), an impeller housing 808, and a controller 810(e.g., controller 206 shown in FIGS. 2 and 3).

In the illustrated embodiment, the motor assembly 800 is a flow-throughmotor assembly. That is, the motor assembly is shaped such that airflows through the motor assembly 800 from an impeller inlet 812, throughthe impeller housing 808 and the motor housing 802 and across the motor804. In other embodiments, the motor assembly 800 may be configuredother than as a flow-through motor assembly, such as a bypass motorassembly.

FIG. 16 illustrates the motor assembly 800 in a disassembled state, andillustrates additional components of the motor assembly 800, such as amotor stator 813, a motor rotor 815, a motor end cap 817, a motor shaft822, and an air vane 819 of the motor housing 802. FIG. 17 is a bottomperspective view of the motor housing 802 with the impeller 806 attachedto the motor shaft 822. The motor assembly 800 is sized, shaped andconfigured to be installed in a vacuum cleaner (e.g., vacuum cleaner100) as a single assembly or unit. That is, once the motor assembly 800is assembled, it is connected to the vacuum cleaner as a unit such thatthe motor assembly 800 generates air flow through the debris chamber(e.g., debris chamber 214) of the vacuum cleaner.

The motor housing 802 provides structural support to components of themotor assembly 800. For example, the impeller housing 808, motor 804,and controller 810 are connected to the motor housing 802. The motorhousing 802 also encloses certain components of the motor assembly 800,such as the controller 810. More specifically, the motor housing 802 ofthe illustrated embodiment is cup-shaped and includes a circular basewall 814 and a radial outer annular sidewall 816 extending upward fromthe base wall and entirely around the motor housing 802. The base wall814 and annular sidewall 816 cooperatively define a cavity 818 in whichthe controller 810 is positioned. The motor housing 802 may also includea radial inner sidewall or boss that supports the motor 804 within themotor housing 802. The base wall 814 includes an opening or aperture 820through which the shaft 822 of the motor 804 extends and connects to theimpeller 806.

In the example embodiment, the motor housing 802 is constructed of anelectrically-insulating material including, for example and withoutlimitation, plastic, such as molded phenolic plastic. In otherembodiments, the motor housing 802 may be constructed of other suitablematerials, including, for example and without limitation, metalized ormetal-plated plastic.

The impeller housing 808 is connected to the motor housing 802 (e.g., tothe base wall 814), and defines an impeller cavity or chamber 824 inwhich the impeller 806 is located. In the example embodiment, theimpeller housing 808 is constructed of an electrically-conductivematerial such as metal, including, for example and without limitation,steel, aluminum, aluminum alloys, and combinations thereof. In otherembodiments, the impeller housing 808 may be constructed of othersuitable materials, such as plastic.

The controller 810 is connected to the motor housing 802 and positionedwithin the cavity 818 defined by the motor housing 802. The controller810 is electrically connected to the motor 804 to control operationthereof. In the illustrated embodiment, the controller 810 includes acircuit board assembly 826 that includes suitable circuit components(e.g., processors, such as processor 304, memory devices, such as memorydevice 306, microcontrollers, transistors, switches, capacitors,resistors) that enable the controller 810 to control operation of themotor 804. The circuit board assembly 826 also includes a ground orcommon circuit that provides a common electrical return for componentselectrically connected to the circuit board assembly 826.

The circuit board assembly 826 of the illustrated embodiment includes aring-shaped printed circuit board 828 that is sized and shapedcomplementary to the cavity 818 defined by the motor housing 802. Withadditional reference to FIGS. 10 and 11, the printed circuit board 828includes a first surface 902, a second surface 904 positioned oppositethe first surface 902, an inner radial edge 906 extending between thefirst and second surfaces 902, 904, and an outer peripheral edge 908extending between the first and second surfaces 902, 904. At least oneof the first surface 902 and the second surface 904 includes conductivetraces and/or conductive pads for mounting or otherwise electricallyconnecting circuit components to the printed circuit board 828. Theinner radial edge 906 defines a central opening 910 sized and shaped toreceive the motor 804 therein. As shown, for example in FIG. 8, when theprinted circuit board 828 is installed in the motor housing 802, a gap912 is defined between the outer peripheral edge 908 and the motorhousing sidewall 816.

The illustrated printed circuit board 828 also includes conductive edgeplating 914 disposed on at least a portion of the outer peripheral edge908. The conductive edge plating 914 is electrically connected to theground circuit of the circuit board assembly 826, and provides anelectrical ground for other components of the motor assembly 800 asdescribed herein. In the illustrated embodiment, the printed circuitboard 828 includes a single segment of conductive edge plating 914 thatextends circumferentially around a portion of the peripheral edge 908.The illustrated conductive edge plating 914 extends around theperipheral edge 908 by an angle of approximately 15°, although theconductive edge plating 914 may extend circumferentially around theperipheral edge 908 by an angle of greater than 15° or less than 15° inother embodiments. By way of example, the conductive edge plating 914may extend around the peripheral edge 908 by an angle of between 0° and360°, between 0° and 180°, between 180° and 360°, between 0° and 90°,between 45° and 135°, between 90° and 180°, between 135° and 215°,between 180° and 270°, between 225° and 315°, between 270° and 360°,between 0° and 45°, between 25° and 70°, between 50° and 95°, between75° and 120°, between 0° and 20°, between 10° and 30°, between 20° and40°, between 30° and 50°, between 40° and 60°, between 50° and 70°,between 5° and 20°, between 15° and 30°, between 25° and 40°, between35° and 50°, between 45° and 60°, and between 55° and 70°. Moreover, theprinted circuit board 828 may include more than a single segment ofconductive edge plating 914 in other embodiments. By way of example, insome embodiments, the printed circuit board 828 includes a plurality ofsegments of conductive edge plating 914 spaced circumferentially aroundthe peripheral edge 908. In yet other embodiments, the peripheral edge908 of the printed circuit board 828 may include a single continuoussegment of conductive edge plating that extends around the entireperimeter of the printed circuit board 828.

The electrically-conductive impeller housing 808 is electricallyconnected to the ground circuit of the circuit board assembly 826 by asuitable electrical connection between the impeller housing 808 and thecircuit board edge plating 914. Connecting the electrically-conductiveimpeller housing 808 to the ground circuit of the circuit board assembly826 facilitates reducing electromagnetic interference between the motorassembly 800 and external electrical components. More specifically, theimpeller housing 808 is secured to the motor assembly 800 through theelectrically-insulating motor housing 802, resulting in the impellerhousing 808 being electrically-insulated or “electrically floating”.Connecting the impeller housing 808 to the ground circuit of the circuitboard assembly 826 prevents or reduces interaction of the impellerhousing 808 with electromagnetic waves (e.g., generated by the motorassembly 800 and/or external sources), which might otherwise resonatethrough the impeller housing 808 and add to the electromagnetic noisesignature of the motor assembly 800.

In the illustrated embodiment, the impeller housing 808 is electricallyconnected to the edge plating 914 by a flexible, compressibleelectrically-conductive conduit 830 (shown in FIGS. 9 and 13) thatextends from the edge plating 914, over the sidewall 816 of the motorhousing 802, and into contact with the impeller housing 808. Morespecifically, the electrically-conductive conduit 830 is positioned inthe gap 912 defined between the printed circuit board 828 and the motorhousing sidewall 816 such that, when the circuit board assembly 826 ispositioned in the motor housing cavity 818, the electrically-conductiveconduit 830 is compressed between the edge plating 914 and the motorhousing sidewall 816.

The flexible, compressible electrically-conductive conduit 830 iscompressible and has a relatively low hardness value (e.g., as comparedto the motor housing 802, the printed circuit board 828, and theimpeller housing 808). As a result, the electrically-conductive conduit830 not only provides an electrical connection between the groundcircuit and the impeller housing 808, but also provides mechanicaldampening between the motor housing 802 and the printed circuit board828.

Suitable materials from which the flexible, compressibleelectrically-conductive conduit 830 may be constructed include, forexample and without limitation, electrically-conductive foams,electrically-conductive rubbers, knitted or wound wire mesh gaskets, andadhesives (e.g., acrylic). In the illustrated embodiment, theelectrically-conductive conduit 830 is an electrically-conductive foam.

Electrically-conductive foams and rubbers can include, for example andwithout limitation, a foam or rubber core and an electrically-conductivecladding wrapped or wound around the core. Suitable materials from whichthe core may be constructed include, for example and without limitation,polyurethane foam, ethylene propylene diene monomer (EDPM) foam,silicone foam or sponge rubber, neoprene foam, and combinations thereof.Suitable materials from which the cladding may be constructed include,for example and without limitation, electrically-conductive fabrics(e.g., polyester embedded with copper and/or nickel),electrically-conductive foils (e.g., aluminum foil), metal-platedfabrics (e.g., fabric plated with copper, silver, and/or nickel),metal-wire mesh gaskets, and combinations thereof. Other suitablematerials that may be used as foils and/or in combination with fabrics(e.g., as plating) include, for example and without limitation, nickel,aluminum, silver, copper, tin, alloys thereof, graphite, carbon, andcombinations thereof.

Additionally or alternatively, electrically-conductive foams and rubberscan include, for example and without limitation, an inherentlyconductive core and/or a core with electrically-conductive materialsembedded or infused within the core. Suitable examples include, withoutlimitation, silver-filled silicone, electrically-conductive wiresembedded in silicone, and electrically-conductive wires embedded inpolyester fabric and/or nylon fabric.

Further, in some embodiments, the electrically-conductive conduit 830includes a compressible knitted metal wire mesh gasket without a core(i.e., without a rubber or foam core). Suitable wires that may be usedto construct a wire mesh gasket without a core include, for example andwithout limitation, copper clad steel, tin-plated copper clad steel,nickel-copper alloys (e.g., Monel), stainless steel, and aluminum.

The electrically-conductive conduit 830 may be connected to the impellerhousing 808 using any suitable connection techniques, including, forexample and without limitation, tacking, clamping, compression fit,adhesives, and combinations thereof. In the example embodiment, theelectrically-conductive conduit 830 is connected to the impeller housing808 by an electrically-conductive adhesive.

In some embodiments, the impeller housing 808 may be electricallyconnected to the ground circuit by an electrical connection other thanelectrically-conductive conduit 830. In some embodiments, for example,the edge plating 914 of the printed circuit board 828 may be raised orprotrude radially outward from the peripheral edge 908 such that theedge plating 914 spans the gap 912 between the peripheral edge 908 andthe motor housing sidewall 816. In such embodiments, the impellerhousing 808 may be electrically connected to the edge plating 914through the motor housing 802. For example, electrically-conductive tape(e.g., copper tape) may be applied to a circumferential section of themotor housing sidewall 816 and extend from the edge plating 914, overthe motor housing sidewall 816, and to the impeller housing 808.Additionally or alternatively, the motor housing 802 may be metalized orotherwise plated in select areas that are in contact with the edgeplating 914 and the impeller housing 808 such that, when the printedcircuit board 828 is installed in the motor housing 802, the edgeplating 914 contacts the metalized portions of the motor housing 802,thereby electrically connecting the edge plating 914 to the impellerhousing 808.

In yet other embodiments, an electrically-conductive adhesive, such asroom temperature vulcanizing (RTV) silicone, may be applied around theperipheral edge 908 to fill the gap 912 between the printed circuitboard 828 and the motor housing sidewall 816. In such embodiments, aconductive tape or metalized motor housing, as described above, may beused to form the electrical connection between the edge plating 914 andthe impeller housing 808.

In some embodiments, the motor assembly 800 may also include anelectromagnetic shield, also referred to as a Faraday shield or cage, tofurther reduce or limit electromagnetic interference between the motor804, controller 801, and external electromagnetic sources. For example,an electromagnetic shield can be electrically connected to the impellerhousing 808, and extend around the motor assembly 800 such that themotor 804 and controller 810 are enclosed within an interior cavity orspace defined by the electromagnetic shield.

The electromagnetic shield may have any suitable construction thatprovides electromagnetic and/or magnetic field shielding of componentsof the motor assembly 800, such as the motor 804 and the controller 810.Suitable constructions for the electromagnetic shield include, forexample and without limitation, metalized plastic, wire mesh, and castor extruded metal. FIG. 14 illustrates an example electromagnetic shield1000 in the form of a metal wire mesh connected to the motor assembly800 shown in FIGS. 8 and 9. FIG. 15 illustrates another exampleelectromagnetic shield 1100 in the form of a metallized plastic motorshield connected to the motor assembly 800 shown in FIGS. 8 and 9.

Electrically connecting the electromagnetic shield to the impellerhousing 808, which is electrically connected to the ground circuit ofthe circuit board assembly 826, ensures that the electromagnetic shieldis connected to the same reference circuit as the controller 810, motor804, and impeller housing 808. The electromagnetic shield may beelectrically connected to the impeller housing 808 using any suitableconnection technique. In some embodiments, for example, theelectromagnetic shield may be mechanically connected directly to theimpeller housing 808 such that a direct electrical connection is formedbetween the impeller housing 808 and the electromagnetic shield.Additionally or alternatively, the electromagnetic shield may beconnected to the impeller housing 808 by an electrical conduit, such asthe flexible, compressible electrically-conductive conduit 830. As shownin FIG. 14, for example, the electrically-conductive conduit 830 thatconnects the edge plating 914 to the impeller housing 808 also connectsthe electromagnetic shield 1000 to the impeller housing 808. Morespecifically, the electrically-conductive conduit 830 is positionedbetween the impeller housing 808 and the electromagnetic shield 1000such that when the electromagnetic shield 1000 is connected to the motorassembly 800, the electrically-conductive conduit 830 is compressedbetween the impeller housing 808 and the electromagnetic shield 1000.

As noted above, the electrically-conductive conduit 830 is compressibleand has a relatively low hardness value (e.g., as compared to the motorhousing 802, the printed circuit board 828, and the impeller housing808). As a result, the electrically-conductive conduit 830 providesmechanical dampening between the impeller housing 808 and theelectromagnetic shield, thereby dampening mechanical vibrations thatwould typically be transferred to the electromagnetic shield through arigid electrical connection (e.g., a bolted or soldered connection).This, in turn, provides sound (noise) mitigation. More specifically, therelatively soft electrical connection provided by theelectrically-conductive conduit 830 dampens the mechanical vibrations ofthe motor 804 and prevents mechanical vibrations from transferring outto the external electromagnetic shield and mounting enclosure, therebyreducing external nuisance sounds (e.g., noise due to vibration). Thisalso reduces mechanical vibrations (e.g., pressure stress), and therebyhelps prevent or reduce fatiguing the mechanical vacuum enclosure.

In some embodiments, the electromagnetic shield includes suitable airhole openings to allow air flow through the motor assembly 800. Theillustrated motor assembly 800, for example, is a flow-through motorassembly. Accordingly, the electromagnetic shields 1000 and 1100illustrated in FIGS. 14 and 15, respectively, include suitable air holeopenings to allow air flow through the motor assembly 800.

The air hole openings in the electromagnetic shield are suitably sizedand shaped to provide a balance between pressure drop due to airflowrestriction and the attenuation capability of electromagnetic waves(e.g., per industry EMC/EMI requirements). In particular, larger airhole openings allow less airflow restriction, but lower the upperattenuation frequency of electromagnetic waves due to the slot antennaeffect being a function of wavelength. Larger air hole openings equateto lower electromagnetic frequency attenuation because high frequency(i.e., smaller wavelength) waves can pass through the larger air holeopenings. The strength of electromagnetic wave transmission is afunction of wavelength in integer or fractional scalar of thefundamental frequency. The unique shielding combination of using severalsmall holes (inherent with a wire mesh) rather than standard machinedslots provides a balance between airflow restriction and highelectromagnetic wave shielding (susceptibility and emissions). Usingmetalized plastic molded motor covers and formed metal mesh aselectromagnetic shields provide an economical means of achieving EMC/EMIshielding requirements, and also provide mechanical dampening throughuse of flexible, compressible electrically-conductive conduits toprovide the electrical connection between the edge plating 914, theimpeller housing 808, and the electromagnetic shield.

Further, in some embodiments, the electromagnetic shield may alsofunction as a flame arrestor. For example, the electromagnetic shieldmay be constructed to provide sufficient heat dissipation and/orabsorption properties to extinguish flames, in the event such flames aregenerated within the motor assembly 800. The wire mesh electromagneticshield 1000 illustrated in FIG. 14, for example, may inherently functionas a flame arrestor, provided proper sealing exists at both the motorinlet and motor exhaust (i.e., the sealing surfaces of the inlet andoutlet have no openings or voids larger than the minimum required toprevent flame propagation). Flame arresting in tandem with the EMC/EMIfeatures of the motor assemblies described herein allow for a vacuumcleaner suitable and safe for industrial, utility, and process(refinery) environments meeting Hazardous Location requirements for allClasses I, II, and III and Divisions 1 & 2, as defined by the NationalFire Protection Association (NFPA) Publication 70, National ElectricCode® (NEC), Article 500 et seq.

Example embodiments of vacuum cleaning systems are described above indetail. The vacuum cleaning systems are not limited to the specificembodiments described herein, but rather, components of the vacuumcleaning systems may be used independently and separately from othercomponents described herein. For example, the vacuum cleaner motorassemblies and associated features described herein may be used with avariety of vacuum cleaning systems, including and without limitation,vehicular or automotive vacuum cleaning systems, wet/dry vacuumcleaners, canister vacuum cleaners, and upright vacuum cleaners.

As used herein, the terms “about,” “substantially,” “essentially” and“approximately” when used in conjunction with ranges of dimensions,concentrations, temperatures or other physical or chemical properties orcharacteristics is meant to cover variations that may exist in the upperand/or lower limits of the ranges of the properties or characteristics,including, for example, variations resulting from rounding, measurementmethodology or other statistical variation.

When introducing elements of the present disclosure or the embodiment(s)thereof, the articles “a”, “an”, “the” and “said” are intended to meanthat there are one or more of the elements. The terms “comprising,”“including,” “containing” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. The use of terms indicating a particular orientation (e.g.,“top”, “bottom”, “side”, etc.) is for convenience of description anddoes not require any particular orientation of the item described.

As various changes could be made in the above constructions and methodswithout departing from the scope of the disclosure, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A vacuum cleaner comprising: a housing; a debrischamber defined within the housing; and a motor assembly connected tothe housing and operable to generate airflow through the debris chamber,the motor assembly including a motor and an impeller; and a controllercommunicatively coupled to the motor, the controller including aprocessor and a memory, the memory including instructions that programthe processor to: operate the motor to cause the impeller to generateairflow through the debris chamber; detect an alert condition; andgenerate a human perceptible audible alert in response to the detectedalert condition.
 2. The vacuum cleaner of claim 1 further comprising apiezoelectric device communicatively coupled to the controller, andwherein the memory includes instructions that further program theprocessor to generate the human perceptible audible alert using thepiezoelectric device.
 3. The vacuum cleaner of claim 1, wherein thememory includes instructions that further program the processor togenerate the human perceptible audible alert by alternating a speed ofoperation of the motor between a first speed and a second speedrepeatedly for a period of time.
 4. The vacuum cleaner of claim 3,wherein the memory includes instructions that further program theprocessor to operate at the first speed by applying full power to themotor, and to operate at the second speed by applying less than fullpower to the motor.
 5. The vacuum cleaner of claim 4, wherein the memoryincludes instructions that further program the processor to operate atthe second speed by applying twenty-five percent of full power to themotor.
 6. The vacuum cleaner of claim 1 further comprising a temperaturesensor positioned to detect a temperature of a drive componentassociated with the motor, and wherein the memory includes instructionsthat further program the processor to: receive the temperature of thedrive component associated with the motor from the temperature sensor;and detect the alert condition when the temperature of the drivecomponent associated with the motor equals or exceeds a temperaturethreshold.
 7. The vacuum cleaner of claim 1 further comprising abattery, and a voltage sensor to detect a voltage output of the battery,and wherein the memory includes instructions that further program theprocessor to: receive the detected voltage output of the battery; anddetect the alert condition when the voltage output of the battery isless than a voltage threshold.
 8. The vacuum cleaner of claim 1, whereinthe memory includes instructions that further program the processor todetect the alert condition when a fault occurs in the motor.
 9. Thevacuum cleaner of claim 1, wherein the memory includes instructions thatfurther program the processor to detect the alert condition when apredetermined maintenance of the vacuum cleaner due.
 10. The vacuumcleaner of claim 1, wherein the memory includes instructions thatfurther program the processor to detect a plurality of different alertconditions and generate a different human perceptible audible alert inresponse to detection of each different alert condition.
 11. Acontroller for a vacuum cleaner including a motor, an impeller, and adebris chamber, the controller comprising: a processor; and a memory,the memory including instructions that program the processor to: operatethe motor to cause the impeller to generate airflow through the debrischamber; detect an alert condition; and generate a human perceptibleaudible alert in response to the detected alert condition.
 12. Thecontroller of claim 11, wherein the vacuum cleaner includes apiezoelectric device, and wherein the memory includes instructions thatfurther program the processor to generate the human perceptible audiblealert using the piezoelectric device.
 13. The controller of claim 11,wherein the memory includes instructions that further program theprocessor to generate the human perceptible audible alert by alternatinga speed of operation of the motor between a first speed and a secondspeed different than the first speed repeatedly for a period of time.14. The controller of claim 11, wherein the vacuum cleaner includes atemperature sensor positioned to detect a temperature of a drivecomponent associated with the motor, and wherein the memory includesinstructions that further program the processor to: receive thetemperature of the drive component associated with the motor from thetemperature sensor; and detect the alert condition when the temperatureof the drive component associated with the motor equals or exceeds atemperature threshold.
 15. The controller of claim 11, wherein thevacuum cleaner includes a battery and a voltage sensor to detect avoltage output of the battery, and wherein the memory includesinstructions that further program the processor to: receive the detectedvoltage output of the battery; and detect the alert condition when thevoltage output of the battery is less than a voltage threshold.
 16. Thecontroller of claim 11, wherein the memory includes instructions thatfurther program the processor to detect a plurality of different alertconditions and generate a different human perceptible audible alert inresponse to detection of each different alert condition.
 17. A method ofoperating a vacuum cleaner including a motor, a battery, an impeller, adebris chamber, and a controller communicatively coupled to the motor,the method comprising: operating the motor to cause the impeller togenerate airflow through the debris chamber; detecting an alertcondition of a plurality of alert conditions detectable by thecontroller, the plurality of alert conditions including a temperature ofthe motor equaling or exceeding a temperature threshold, a voltage ofthe battery being below a voltage threshold, a motor fault occurring,and a predetermined maintenance being due; and generating a humanperceptible audible alert in response to the detected alert condition.18. The method of claim 17, wherein generating the human perceptibleaudible alert in response to the detected alert condition comprisesalternating a speed of operation of the motor between a first speed anda second speed different than the first speed repeatedly for a period oftime.
 19. The method of claim 17, wherein generating the humanperceptible audible alert in response to the detected alert conditioncomprises generating the human perceptible audible alert using apiezoelectric device.
 20. The method of claim 17, wherein generating thehuman perceptible audible alert in response to the detected alertcondition comprises generating a different human perceptible audiblealert for each alert condition of the plurality of alert conditionsdetectable by the controller.